2. amps-preamps
  3. 1249244359

Can you lower gain requirements on tube amp?

I have a Cary Rocket 88R tube amp (30w tri/60w UL) that requires more gain then I'm used to to get to 'realistic' (ie louder) listening levels (90db+). I have a Promitheus Ref4 TVC passive that I love, but volume knobs at full throttle sometimes still isn't loud enough. I literally need it go to 11.

Specs on the TVC state -48db to 0. I'm curious if I can do something to the amp, ie roll different driver tubes or??.... to decrease the gain requirements? I've also contacted Nicholas at Promitheus to see if he can modify the gain, haven't heard back yet.

I will also state that my speakers are Usher 6381 rated at 87db/8 ohm. The Cary drives them well, but wondering if the speakers sensitivity relates to loudness (ie more sensitive speakers would generate more loudness at the same volume settings?)

I don't want to introduce a tubed buffer into the mix -- tried it and didn't like the sound. Want to work with what I have if possible. Thanks

FYI tubes in the Cary are:
kt-88 output
12BZ7 / 12AX7 / 12AY7 drivers (currently using 12BZ7)
EL-84 / 6BQ5 current source
tholt
newbee
4,767 posts
 
Tholt, re DAC/CDP output voltage - I am presently running 4 digital sources. One with 2v, one with 2.2v, one with 3.5v and the latter varible at 2,4 & 6v. I have never measured the difference in db's at the speaker between each output level so this is a WAG, but I think the increase from 2 to 3.5v (or 4v) would be at least 9 or more db's. On the Wadia I would use either the 4 or 6v setting to drive the amp direct. This has nothing to do with recording level on the CD although that can vary at times. But, FWIW, personally I prefer to run my Wadia thru an active lines stage as well and I use the 2v setting.

BTW, also IMHO, I think amps with a .5v imput sensitivity are far more compatable with passive line stages, and interestingly less so when used with high gain active line pre-amps. Thats how its has worked out for me anyway.
marakanetz's avatar
marakanetz
5,473 posts
 
I have SS Sunfire Symphonic reference amp with 1.2V input sensitivity. Virtually there's no way that it will sound right with passive preamplification.
When I used to have VTL MB100, they will sound at their best either with unity gain active preamp or passive(.7V input sensitivity).
rleff
1,065 posts
 
Did you talk with Dennis at Cary;maybe he can mod your amp to handle the input voltage swing that your preamp is outputing to the Cary's.
undertow
1,033 posts
 
Dump the TVC for a true active preamp with good impedance specs. That will solve it the fastest, and probably cheapest at this point, plus add some missing dynamics and body which is why your looking to do this all in the first place!

Good luck
kirkus
502 posts
 
I have never measured the difference in db's at the speaker between each output level so this is a WAG, but I think the increase from 2 to 3.5v (or 4v) would be at least 9 or more db's.
Doubling the voltage is an increase of 6dB.
More to discover